Question
I reside in Illinois.  I have two big potted alstroemeria (Mathilde Princess and Theresa Princess Lillies) plants.
How do I winterize them.  Do I separate into smaller pots and bring in the house or do I leave in original post and cut them back and place in garage over the winter.  Any additional winterizing tips would be greatly appreciated.

Answer
Hi Arleen,
Thanx for your question.  Most references indicate that Alstroemerias are only hardy to Zone 7.  I've grown then here in Zone5/6 and they did not overwinter.  I am reading that other folks have successfully overwintered them in Zone 5 so, they must be heavily mulching them.  Were it I, I would drag the pots into an unheated garage or shed and mulch the pot.  The rhizomes are brittle and easily damaged so lifting in the fall (like you do with cannas and dahlias) is not recommended.  The key is to keep the soil from freezing.  I've overwinted gladioli and calla lilies before by placing lots of hay or leaves on top of the growing area.  Because your plants are in pots, I think it is safer to move them into an unheated garage or shed.  Let the first frost kill them back and then, snip off the dead growth.  In the unheated garage or shed, you will have to check periodically to make sure the soil doesn't dry out completely.  So you'll need to moisten the soil every couple weeks or so.  In the spring, move the pots back outdoors after the last frost and begin watering and feeding by side dressing plants after they have emerged, with well-composted manure.  I hope this helps.
Tom